Good cheap lens, with small weaknesses

As a commercial photographer, I use mainly powerful lenses, which unfortunately also often have a large weight in addition to a high price and are very limited in the zoom range. On the go and traveling professional such lenses therefore are not really the best choice. Since space is limited and you do not want to pack a whole backpack for weight reasons, here an alternative is necessary, on the one hand provides acceptable image quality, but on the other hand, is compact, lightweight and low priced. For the sake of image quality I gave up a single> Soup Zoom
For general manufacturing quality can be said that there is a very high quality look. Zoom and focus ring are sitting tight, however, are designed to steep for manual focusing. The lightweight, but high-quality, stable plastic is coated with a kind of velvet and acts, together with the golden lettering, almost noble. A metal bayonet completes the positive first impression. When passing through the zoom range of the front tube extends only a few centimeters, which could act against accidentally bumped against it. The front lens rotates, thanks to internal focusing, not with, thus enabling the use of polarizing filters Circular. The sun visor as standard supplied is sufficiently large to prevent flares and ghosting largely. The grooved surface on the inside thereby reduces reflexes that might emanate from the sun visor itself.

The optical qualities of the lens can be broadly say that they met my expectations in relation to price and partly exceeded. The biggest shortcoming remains the focus. It is not so that the lens produced blurry pictures, but just at full aperture, it delivers but noticeably soft images across the entire image field. To a stage dimmed the sharpness improved somewhat but remains a bit behind comparable lenses (eg, Tamron 70-300). Advantageously, the resolution leaves a fairly uniform impression in the picture and not fall further toward the edges / corners, suggesting a good centering. Its strengths, the Sigma 50-200 from the field of error correction. Namely, there are hardly any available. Vignetting (Randabdunklungen) can be seen only at full aperture and at the short end (50 to 70 mm), but can be corrected very well. CAs are almost a non-issue for the Sigma. Otherwise common in telephoto lenses, can be found fringing only very pronounced contrast edges (chiaroscuro). Dimmed and under normal shooting conditions play the CAs not matter. The distortion is kept within limits. The lightweight ton (short end) or pillow shape (at the long end) is hardly noticeable and can be corrected quite easily. Flares and ghosting by light reflections are very small and inconspicuous when the standard sun visor is used. Contrasting the Sigma is tuned neutral. Although cooler than comparable Tamron products, but still quite enjoyable. Contrasts and colors ensures the lens is very good.

The OS image stabilizer delivers good results. An improvement by 2 f-stops does not quite reach the one built into the camera stabilizer (approximately +3 EV), but it offers a stabilized viewfinder image even with Sony and Minolta. Therefore, I can practice no negative criticism of quiet stability itself. Even the slight rattle of the movable lenses (when turned off) does not interfere, but was at first but unfamiliar.

Most negative point is the autofocus drive. Although AF is extremely accurate and barely audible, but it takes an eternity until the HSM engine has passed through completely the focus distance. Straight from HSM I had clearly expected me here longer. Provides here, surprisingly, the pinion drive of Minolta and Tamronobjektive faster speeds. Ultimately, the slow focus was the main reason for me> only
Summary:
+ Acceptable sharpness across the entire image area / good centering (ideal at 5.6 to 11.0 f)
+ Little chromatic aberration
+ Low distortion
Already dimmed to 1EV barely visible Vignette
+ Quieter and more accurate focus, hardly 'pump'
+ Super processing
+ Good weight (rel. Easy)
- Visible soft images at maximum aperture
- Very slow HSM AF motor
- To steep translation of the manual focus

In conclusion, a good throw that Sigma has succeeded here, which can be almost a friend. I can appreciate to have caught a good specimen me very happy. If even in this perspective the typical sigma quality fluctuations, the buyer needs a thick skin to survive the Sigma Service. Even if I can recommend it to anyone budget conscious buyer this lens in my view, yet the experience left me with the Sigma-Service and the 18-50 HSM (see review) dominated. Despite awarded 4 stars here, remains a brand that I have unfortunately bought a first and last time for me Sigma.